1. Field of the Invention:
The present invention relates to an electrode for use in an electrochemical cell employed to produce electrical power. More particularly, the present invention relates to a bipolar electrode for use in a rechargeable lead-acid battery.
2. Brief Description of the Prior Art:
U.S. Pat. No. 3,817,788 to Eckerbom, et al. discloses a bipolar electrode which has a support wall of insulating material and two current conductors of large surface area on opposite sides of the support wall. The two current conductors are connected electrically together by a large number of through connectors which provide a substantially uniform current density throughout the current conductors. Negative active material is on one current conductor, and positive active material is on the other current conductor.
U.S. Pat. No. 4,178,216 to Nordblom, et al. discloses a bipolar electrode support structure for use in a lead acid battery. The structure is comprised of a porous matrix of valve metal impregnated with lead or a lead alloy. At least one surface of the structure has a rim portion which has little or no exposed lead.
U.S. Pat. No. 4,211,833 to Einstein discloses a bipolar battery comprised of at least two battery cells. Each battery cell is comprised of a plurality of electrodes. These electrodes are comprised of at least two cellular end plate electrodes and at least two interstitially located single pole electrodes. A continuous, sheetlike insulator is located in an alternating, woven disposition within each of the cells between all adjacent electrodes to provide electrical separation. The end plate electrodes of adjacent cells are of opposite polarity and comprise a single, bipolar electrode.
Conventional bipolar electrode devices, such as those taught by the above references, have not been completely satisfactory. Expansions and contractions of the electrode during the charge and discharge operations can cause creep distortion at the seal interface between the individual cells within the battery. A resultant distortion corrosion allows leakage of electrolyte between the cells which causes intercell discharge.
In addition, conventional bipolar electrodes have been susceptible to perforations through the thickness of the electrode. This perforation can cause intercell discharge. Insulators have been employed to prevent perforation and leakage of electrolyte, but these insulators have also undesirably reduced electrical conduction across the electrode.